We will continue our studies on the mechanism of transmembrane signalling of cholera toxin in cloned, differentiated and spontaneously-transformed RL-PR-C repatocytes. We will also examine the effects of cell density and on spontaneous transformation of these cells on cAMP production and on receptor-adenylate cyclase coupling. Another project involves the use of photoaffinity probes of insulin and glucagon to identify the specific and non-specific receptors of these hormones on PAGE gels, with the goal in mine of studying the biosynthesis of their receptors. Another group will be studying the properties and regulation of the glucagon receptor in hepatocytes.